High resolution PET imaging for Brain and other organs continues to undergo enormous technological advances. One example is the High Resolution Research Tomograph (HRRT) the highest resolution and sensitivity human brain dedicated scanner which was recently installed under the auspices of an NIH SIG, 1S10RR017219-01A1, at Johns Hopkins University. The computational demands for the current reconstruction software and potential alternative are challenging but feasible. We are requesting the computer hardware to support several NIH funded projects employing emission tomography (PET/SPECT). Part is to double our current 32 node cluster size, allocated for HRRT routine reconstruction, which will substantially improve throughput without sacrificing quantitative accuracy for the large number (over 26) of animal and clinical protocols to be supported. These demands will become even greater as our NIH research studies shift from the other NIH NCRR supported scanner, and the GE Advance becomes obsolete (now 8 years old). Secondly, a number of NIH projects require more computational time. This includes further improvements in HRRT quantitation including head movement correction (the HRRT has over 207 slices) and appropriate corrections including scanner, etc., and more accurate reconstructions using Linux based program require a parallel effort on a development only cluster. Furthermore, 4 NIH SPECT/PET projects involving intensive simulations and SPECT reconstructions are needed. Hence we are requesting increasing this to a 24 node cluster. This will also incorporate algorithm development by collaborators working on similar algorithms in heart and cancer. All of these projects are supported by a total of 30 NIH funded, pending or pilot studies needing these computing facilities for human, animal or calculation tomography research. By providing this additional equipment this will allow full utilization of an already funded NCRR PET scanner while continued work by both basic as well as applied brain and other NIH related research and extend the limits of this high resolution scanning into applications not realized before. [unreadable] [unreadable] [unreadable]